ISLAMABAD: A new earth-filled dam for irrigation will emerge on the map of Balochistan aimed at improving the agricultural productivity of the rain-fed area on the tributary of Zhob River.

The proposed Sri Toi Water Storage Dam and irrigation project will be located in Mir Ali Khel Union Council, about 62km northeast of Zhob on Sri Toi River.

The project has been submitted to the Asian Development Bank which is evaluating it for financing. The Balochistan Irrigation and Power Department (BIPD) will execute the project.

It is expected that the construction will cover the command area up to 4,027 hectares, besides ensuring sustained water supply to the present command area, being cultivated on a seasonal basis by growing vegetables and grains.

The proposed reservoir would recharge the subsurface flow of karez, shallow wells and tube-wells, protect the agriculture land and human settlements from devastation of floods during flood seasons and develop grazing zones for livestock. The stored water will support drinking, agriculture purpose and other domestic uses.

The annual average availability of water is nearly 57 million cubic metres with a catchment area of 971 square kilometres. According to the project document, the earth-filled dam will have clay core and will be 66 meters in height on Sri Toi River. A spillway in a length of 135m from the left abutment of the dam will be constructed.

The main objective of the project is supply of irrigation water to the project area. Most of the area can be considered poor, subsistence farming is the economic mainstay, so the project will have a major impact on the welfare of local people.

Agriculture and livestock are main sources of income of local people. The community of the sub-project area is composed mainly of Mando-Khel tribe of Pashtoons. However, the sub-project will have a significant impact on a relatively remote community with a very low level of income. There are significant markets within reach and the area has potential for wheat and vegetables which are able to offer good rates in the market.

Four sites were considered for the proposed dam, however, Sri Toi Water Storage Dam was found to be the best suitable site. The proposed and existing command areas in the selected sub-projects come out to be 4,027 hectares for Sri Toi Dam project. The command areas for Ahmedzai Perennial and Floodwater Irrigation (859 hectares), Sabakzai Dam Irrigation Project (3,350 hectares) and Killi Sardar Akhter — Perennial and Floodwater Irrigation (252 hectares) are again much lower than the selected scheme.

In case the proposed project is not implemented, the socio-economic conditions will not change as such. With the increasing population and scarcity of resources, residents are forced to abandon their homes in search of livelihood and grazing grounds for their cattle stock.

From the environmental perspective, the project site comprising of dam pondage area as well as irrigation channel and proposed land for irrigation are arid in nature having little or no rain and too dry to support vegetation. Water availability is scarce in area hence the proposed project will contribute positively to the project area.

The proposed project aims to elongate time frame and in due course the water storage dam would support ecology in longer time span. The construction of the dam will change land use of the project site. Presently the project site is barren land with low to no vegetation, shrubs or non-migratory ecology species.

It has been estimated that the dead storage capacity that will deplete in the early 10 years is computed as 6.49 million cubic meter. The annual sediment load has been computed as 0.901 million short tons. The life of the dam has been estimated at approximately 80 years.

Published in Dawn, February 5th, 2018